Process of producing printing-plates.



UNITED STATES PATENT OFFICE. I

BOGDAN GISEVIUS, OF BERLIN, GERMANY.

PROCESS OF PRODUCING PRINTING-PLATES.

T 0 all whom it may concern:

Be it known that I, BOGDAN GISEVIUS, a subject of the German Emperor, resident of Berlin, Germany, have invented certain new and useful Improvements in Processes of Producing Printing-Plates, of which the following is a specification.

In the processes hitherto in use, for roducing impression printing plates in wiich almost alwa s metal plates .are used, there is one difficu ty to be overcome, namely that resulting from that step in the process in which the plate is coated with the first sensitized layer and in which by the washin", the picture of the drawing is produced. In this ste the surface of the plate is so influence by contact with the materials of the sensitized layer that its surface is made more or less averse to receiving the printingink. One of the most important points in these processes is to make the picture roduced in the sensitized layer dis ose to receive the printing ink readily. his difficulty is overcome in different ways in the different processes, and in a more or less reliable and easy manner. The surface of the picture is either treated chemically, that is to say, desacidified and the exceedingly thin film on the surface, which alone causes the re ugnance against the printing ink, dissolve or, secondly, the surface influenced by the sensitized layer is removed mechanically by a grinding operation, or thirdly, the surface is coated with a special matter which permanently adheres to the plate and readily receives the rinting-ink, as described in the United States Patent No. 755,225 granted to me March 22, 1904. The present invention solves this question in the most simple and direct manner by adding to the sensitized layer a matter or an acid which counteracts, from the start, the influence which the first layer or coat has on the plate, and without any mechanical or chemical rocess, makes the picture produced in t e sensitized layer, susceptible to absorb fatty substances.

In m* process the sensitized layer with which the metal plate is to be coated, consists of a mixture of glue, any suitable acid and the double chromate of potassium or ammonium. If a design is laid upon a metal which has been coated with this mass and dried, the black lines of this drawing shut off the light so that after the exposure, the

Specification of Letters Patent. Application filed May 15, 1905. Serial No. 260,667.

Patented Feb. 23, 1909.

places which were covered by the lines of the drawing may be washed off in cold water while the remainder of the surface will be made insoluble in the water. At the places covered by the drawing the metal is quite bare after having been exposed and washed, while every other part of the plate, that is to say the back-ground, is covered by the glue mixture. Therefore, when, after washing, the plate in this condition is treated in a mechanical or chemical way, the lines of the drawing ma be rendered imperfect so that wh le the p ate is being polished with a soft substance, the picture Wlll in all probability be attacked and altered also. For this reason, such polishing of the plate is in the highest degree undesirable and should be avoided.

The sensitized layer is applied to the plate in the usual way, then exposed for the picture and washed with cold water, after which the plate is coated with any suitable fatty substance, which is absorbed in the washed icture, and which, after a short time. al ows of removing the exposed portions of the sensitized layer,..by dip ing the plate into an acid bath, in the case of aluminum into weak nitric acid, which does not affect the fatty coating. The plate is thus made ready for rinting in two short operations. As the sensitized layer is not sub ected to a mechanical or chemical action subsequently to the fixing of the picture in the sensitized layer,

this layer may be very ess as a whole is made delicate.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. The rocess of producing impression printing p ates which consists in adding a suitable acid to an actinic substance capable of being rendered insoluble by light, coating a plate with the mixture so formed, exposing the plate under the desired design, in developing the design, said development consisting in washing out the unexposed portions of the coating mixture, then in applying a fatty substance to the face of the plate so produced next in subjecting it to an acid bath, and finally in removing the insoluble portions of the surface.

2. The process of producing impression printing plates which consists in adding a suitable acid to an actinic substance comthin, so that the procfar more rclme and lOO posed of glue and bichromate of potassium, 1n applying a layer of said mixture to a late, next in exposing the plate under the esign to be reproduced and in developing the design so produced in such manner as to adapt the unexposed portions of the plate to constitute the printing surface.

3. The process for manufacturing printing plates which consists in coating the WVitll a size containing acid and allowing the same to dry, next in exposing the plate under an original drawing, then in washing out the portions covered by the lines of the plate drawings whereby the portions of the metal plate beneath said lines are without further treatment adapted to receive and retain the printing ink, and finally in removing the ex posed coating from the plate.

In testimony whereof I have signed my name to this specification in the presence of go i two subscribing witnesses.

BOGDAN GISFNI US.

Witnesses VVOLDEMAR HAUPT, HENRY HASPER. 

